1. Field of the Invention
The present invention relates to a printer capable of executing a continuous print mode by using an ink sheet in which a plurality of ink portions are arranged in order in a conveyance direction, a control method thereof, and a storage medium.
2. Description of the Related Art
Many printers capable of printing image data captured by a digital steel camera, a digital video camera, or a mobile phone, have been placed on the market. An example of a printing system employed by such a printer is a thermal transfer system.
In the printer of the thermal transfer system (hereinafter, thermal transfer printer), a plurality of heating elements arranged in a main scanning direction of a thermal head are selectively heated according to the image data. Ink of an ink sheet is melted by the heat to be transferred to a sheet having an ink receptive layer on its surface, thereby printing an image of one main scanning. In this case, an image for each main scanning is printed while conveying the sheet in a sub-scanning direction, and an image of a predetermined size is printed.
A sublimation thermal transfer printer among the thermal transfer printers converts the ink of the ink sheet from a solid substance to gas, and sticks the ink to the sheet to print the image. Such a thermal transfer printer can change a density of one pixel by controlling the amount of heat applied to the thermal head and the number of its driving times. Thus, the thermal transfer printer can express a smooth image with high gradation, and is often used in photo printing.
In an ink sheet illustrated in FIG. 9, ink portions (sublimation dyes) of yellow (Y) 801, magenta (M) 802, and cyan (C) 803 are frame-sequentially arranged to form an image on its base material in a longitudinal direction. At the end thereof, there is disposed an overcoat (OP) portion 804 that is a hot-melt ink portion to protect an image formation layer transferred to a sheet. Search position detection markers 805 are respectively arranged between the ink portions 801 and 802 of Y and M, between the ink portions 802 and 803 of M and C, and between the ink portion 803 of C and the OP portion 804.
FIG. 10 illustrates a printing example of an image using the ink sheet. When one image is formed by using such an ink sheet, the image is thermally transferred to a sheet by using the ink portions 801 to 804 of Y, M, C, and OP as a set. In an ink cartridge for housing the ink sheet, therefore, sets of ink sheets each including the ink portions of 801 to 804 of Y, M, C, and OP are arranged in a repetitive manner for a printable number.
Generally, a length of the sheet including the ink portions 801 to 804 of Y, M, C, and OP is set so that an image can be printed on a longitudinal size of a sheet of a printing target.
As discussed in Japanese Patent Application Laid-Open No. 2004-082610, in a thermal transfer printer that uses continuous paper as a sheet, in addition to a normal image, an image 910 of a panoramic (wide) size using the ink portions 801 to 804 of Y, M, C, and OP for a two-surface amount illustrated in FIG. 10, can be printed. An arrow A indicates a sheet conveyance direction during printing, and an arrow B indicates a sheet conveyance direction during feeding-back (sheet returning to a printing start position).
In FIG. 10, a right screen (first screen) 911 of the panoramic image 910 is formed by transferring sublimation or hot-melt ink of the Y, M, C, and OP portions 801, 802, 803, and 804 of the ink sheet of a first surface to the sheet. Similarly, a left screen (second screen) 912 of the panoramic image 910 is formed by transferring sublimation or hot-melt ink of the Y, M, C, and OP portions 801, 802, 803, and 804 of the ink sheet of a second surface to the sheet.
In the thermal transfer printer, for example, when the hot-melt ink of the OP portion is applied again by mistake on a printed sheet, the ink sheet sticks to the printed sheet, causing a jamming problem of the printed sheet or the ink sheet. Such a problem occurs when an electric power failure or a forcible termination occurs during printing and supplying of power is cut off, and printing is performed again from the sheet in the middle of printing after reactivation.
To prevent such a problem, processing of inspecting remaining sheets in a printer engine before printing to be executed immediately after activation, and discharging of the remaining sheets, if detected, is performed. In the thermal transfer printer that uses the continuous paper as the sheet, processing of detecting a size of the ink sheet by an ink sheet cartridge, thereby cutting the sheet by a specific sub-scanning length to discharge the sheet, is performed.
In the thermal transfer printer capable of executing the panoramic size print mode, to process remaining sheets, which surface of the ink sheet has been used to print an image on the remaining sheet should be determined. As one of such determination methods, a print state is recorded in a read-only memory (ROM) for each end of printing of one screen.
However, when state recording fails due to an electric power failure or a forcible termination, not only writing of a print state may fail but also ROM data containing activation information may be destroyed, directly leading to a printer failure.
To surely prevent sticking of the ink sheet to the sheet caused by reprinting in a printed area, the printer is only required to cut the sheet by a printable maximum length, and then discharge the sheet. In this case, however, even unprinted sheets may be cut, causing a problem of sheet wastes.
Japanese Patent Application Laid-Open No. 2006-315215 discusses a technique of preventing reprinting on a printed sheet by using a sensor for detecting color changes of printing paper having a heat-sensitive sheet material to be changed in color by thermal energy and stuck to an unprinted area, and a heat-sensitive sheet. However, sticking the heat-sensitive sheet material to the printing paper causes a problem of a cost increase for the printing paper.